EK Chem In-Class #35

[dougkaye]

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EK Chem Lecture 2 in-class exam, #35. The answer key states that the concentration of catalyst can increase the rate of a reaction. None of our formulas or concepts supports that claim! They use a Michaelis-Menten graph to support their argument, but that is only vs. rate, NOT [enzyme]. I have read in other sources that [enzyme] doesn't influence rate. Is this just EK errata or am I missing something?

 

[WhiteWashed]

EK Chem Lecture 2 in-class exam, #35. The answer key states that the concentration of catalyst can increase the rate of a reaction. None of our formulas or concepts supports that claim! They use a Michaelis-Menten graph to support their argument, but that is only vs. rate, NOT [enzyme]. I have read in other sources that [enzyme] doesn't influence rate. Is this just EK errata or am I missing something?

imagine a trying to chop up a whole bunch of vegetables. It would take a while. Now imagine using a food processor to chop it up.

Which would be faster: using 1 food processor to chop up all the vegetables or using 10 food processors to chop up the vegetables?

a catalyst can only catalyze so many reactions at a time. More catalyst can help the turnover rate of the enzyme.

 

[dougkaye]

I am still not convinced. If you have a chemical reaction where the catalyst is not saturated, then increasing the concentration of catalyst will NOT make the reaction go faster. On the other hand, if you have a fixed amount of catalyst, increasing the concentration of substrate will ALWAYS increase the rate of reaction until you reach a theoretical Vmax. EK shouldn't apply a rule that only works in certain situations to a more general discussion of reaction rates. If someone can actually cite a source that states otherwise please let me know 😉

 

[Rabolisk]

Did the passage state that the catalysts are not saturated?

 

[dougkaye]

didn't mention any specifics, so it was using this as a general rule applicable to all situations. my argument is that change in [cat] doesn't always increase rate, but still hoping for someone to clarify with a non-vegetable cutting argument.

 

[Rabolisk]

What was the exact question and answer choices? Perhaps this answer choice was the BEST answer choice, even if it isn't always CORRECT.